1. Field of the Invention
The present invention relates to a utility knife, in particular, an improved utility knife with a safety lock, with which a user is able to securely lock an outer body of the knife without worrying that the utility knife may fall apart when an external force is accidentally exerted thereon.
2. Description of Related Art
A conventional utility knife for woodworking is shown in FIG. 5. A utility knife of this kind has a retainer (30) pivotally received between an upper cover (10) and slide (40) movably received in a lower cover (20) which is detachably connected with the upper cover (10). The retainer (30) has a through hole (31) defined in the end thereof and the slide (40) has a wedge (41) detachably extending through the through hole (31), such that when the retainer (40) is pushed in a direction toward the lower cover (20), the slide (40) will first be forced to slide away by the insertion of the retainer (30) and then the slide (40) will return and insert into the through hole (31) of the retainer (30) due to the force of a recoil spring (21). When the upper cover (10) is to be disassembled from the lower cover (20), a user only needs to push the slide (40) along the lower cover (20) to force the wedge (41) to separate from the through hole (31) of the retainer (30). Because the retainer (30) is pivotally in connection with the upper cover (10), the upper cover (10) and the lower cover (20) are easily assembled and disassembled. When the upper and lower covers (10, 20) are assembled, the only force applied therebetween is the securing force between the retainer (30) and the slide (40). Therefore, it is still quite easy to separate the upper cover (10) and the lower cover (20), especially when an external force is accidentally applied, e.g. the knife accidentally falls on the ground. The blade (51) is held by a carrier (52) which is movably received between the upper cover (10) and the lower cover (20). Once the upper cover (10) and the lower cover (20) are separated with each other, the blade (51) may come out and hurt someone nearby.
In order to mitigate and/or obviate the above disadvantages, the invention provides an improved utility knife having a safety lock to strengthen the connection between the upper cover and the lower cover.